The Monocots Basal and “Petaloid” Groups

The Monocots
Basal and “Petaloid” Groups


Synapomorphies of Monocots

• Root system adventitious
• One cotyledon
• Stems with scattered vascular bundles (no
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secondary growth); herbaceous
Leaves parallel-veined with a sheathing
base
Flowers pentacyclic (5 whorls), trimerous
Sieve cell plastids with several cuneate
protein crystals
Lots of molecular support for monophyly


Additional features of monocots
• Leaves formed from the basal end of the
leaf primordium
• Usually with monosulcate pollen
• Lack glandular teeth on leaves


Basal and “Petaloid” Monocot Groups

Order Acorales
Acoraceae
Order Alismatales
Araceae
Alismataceae
Order Liliales
Liliaceae
Order Asparagales
Agavaceae
Alliaceae
Amaryllidacaee
Iridaceae
Orchidaceae


Basal Monocots:

Acorales: Acoraceae
not required

• Widespread, temperate throughout tropical
regions
• Aquatic herb
• Diversity: 1-3 spp. in 1 genus (Acorus)
• Flowers: typical of Araceae, coalesced into a
spike-like spadix
• Significant features: Sister to the rest of the
monocots; contain ethereal oils.
• Special uses: none
• Family not required, but Acorus

evolutionarily important


“Petaloid” Monocots—Alismatales:

Araceae
(The Arum Family)

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Cosmopolitan; greatest diversity in tropical regions
Terrestrial and aquatic herbs, vines, epiphytes,
floating aquatics
Diversity: 3,300 species, 109 genera
Flowers: many, small; lacking extensive perianth,
carpels 2-3; if unisexual then spatially separated in
inflorescence or sometimes plants dioecious
Significant features: inflorescence – spadix subtended
by a spathe (specialized leaf)
Special uses: many ornamentals; Colocasia as food
Required taxa: Arisaema, Lemna


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-spathe margins overlapping below, spathe mostly arched
above,
striped or marked
-spadix usually slender and elongate
-flowers unisexual and only at the base of the spadix

Araceae: Lemna and friends
•Reduced plant body: no stem or leaves;
sometimes no roots
•Rarely flower


“Petaloid” Monocots—Alismatales:

Alismataceae : not required
(The Water Plantain Family)

• Widely distributed
• Aquatic & wetland rhizomatous herbs
• Number of species: 88 species, 15 genera
• Flowers: sepals & petals distinct, many
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apocarpous carpels; flowers or floral axes

often whorled
Significant features: rhizomatous
Special uses: ornamental aquatics
Family not required


Liliales
• Nectaries at base of tepals
• Spots on tepals
• Extrorse anthers


“Petaloid” Monocots—Liliales:

Liliaceae
(The Lily Family)

• Widely distributed in temperate regions of the
Northern Hemisphere
• Perennial herbs, usually with bulbs and
contractile roots
• Number of species: ca. 600 species, in 16
genera
• Flowers: tepals 6, distinct, carpels 3, stamens 6
• Significant features: Fruit a loculicidal capsule,
sometimes a berry; no onion-like odor
• Special uses: many ornamentals
• Required taxa: Erythronium, Tulipa

ASPARAGALES


Asparagales
• Herbs to woody;
sometimes succulent
•Tepals not spotted
•Nectaries septal
•Style usually 1, simple
•Seed coat collapsed
to + present
•Phytomelan crust
(seeds black) from dry
fruits; not in fleshy fruit

vs.

Liliales

• Herbs; not succulent
•Tepals often spotted
•Nectaries at base
of tepals/filaments
•Styles 1 (trifid) or 3
•Seed coat present
•No phytomelan crust
(seeds not black)


“Petaloid” Monocots—Asparagales:

Alliaceae
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(Onion Family)
Widely distributed in temperate and tropical regions;
also semiarid.
Bulb-forming herbs with basal, usually narrow leaves
Number of species: ca. 600 species, in 13 genera
Flowers: Often showy, tepals 6, stamens 6, 3 connate
carpels, ovary superior; inflorescence umbellate; fruit
a loculicidal capsule.
Significant features: sulfur-containing compounds
(onion odor)
Special uses: onion, garlic, leek, shallots, chives, used
as food & seasonings; ornamentals
Required taxa: Allium


“Petaloid” Monocots—Asparagales:

Amaryllidaceae
(Amaryllis or Daffodil Family)

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Widely distributed in temperate to tropical regions;
maximal diversity in South Africa, Andean South
America, and the Mediterranean
Bulb-forming herbs with contractile roots
Number of species: 850 species in 59 genera
Flowers: often showy; tepals 6; stamens 6,
sometimes adnate to perianth; carpels 3, inferior
ovary; fruit usually a loculicidal capsule
Significant features: special alkaloid compounds
present
Special uses: many ornamentals ( Narcissus,
Hippeastrum)
Family not required


“Petaloid” Monocots—Asparagales:

Iridaceae
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(The Iris Family)
Widespread in tropical and subtropical regions;
absent in Australia.
Perennial herbs forming rhizomes, corms, or bulbs
Number of species: ca. 1,750 species, 67 genera
Flowers: radial or bilateral, showy; tepals 6, outer
tepals often differentiated from inner; stamens (2) 3,
opposite outer tepals; carpels 3, fused into an
inferior ovary; fruit a loculicidal capsule
Significant features: leaves unifacial or terete,
equitant
Special uses: many ornamentals; saffron ( Crocus
sativus)
Required taxa: Iris


“Petaloid” Monocots—Asparagales:

Orchidaceae
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(The Orchid Family)
Widespread throughout the world; maximal diversity in
tropical regions
Primarily epiphytes; some terrestrial herbs, occasionally
vines
Diversity: ca. 20,000 species in 700-800 genera
Flowers: showy, usually resupinate, bilateral, the median
inner tepal differentiated into a labellum (lip); highly modified
androecial and gynoecial parts, fused into a column; pollen
grouped into soft or hard masses (pollinia) united by a stalk
into a pollinarium; ovary inferior; placentation parietal; fruit a
capsule dehiscing with (1-)3 or 6 slits; seeds tiny, dust-like
Significant features: among the most specialized of all
angiosperm flowers
Special uses: many ornamentals; Vanilla
Required taxa: family only


The Monocots
Commelinid Monocots


Commelinid characters
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Special type of epicuticular wax

Starchy pollen
UV-fluorescent compounds in the cell
walls
• Starchy endosperm (except in the palms)
• Lots of molecular support


Commelinoid Monocot Groups
Order Arecales – Palms
Arecaceae (Palmae)
Order Commelinales – Spiderworts,
bloodworts, pickerel weeds
Order Zingiberales – Ginger, banana, and
allies
Order Poales – Bromeliads, Cat-tails,
Rushes, Sedges, and Grasses
Typhaceae
Juncaceae
Cyperaceae
Poaceae (Gramineae)


Commelinoid Monocots:

Arecales: Arecaeae (Palmae)
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Widespread throughout tropical and warm temperate
regions
“Trees” or “shrubs”, typically unbranched
Diversity: ca. 2,000 in 190 genera
Flowers: usually sessile, in compound-spicate
inflorescences, these subtended by a bract (spathe);
ovule 1 per locule
Significant features: Leaves alternate or spiral, blades
plicate, splitting in a pinnate or palmate manner
Special uses: coconut (Cocos nucifera), date
(Phoenix dactylifera), rattan (Calamus), oils and
waxes, ornamentals
Family not required


Arecaceae
•Numerous small flowers
•Spathes + compound-spicate inflorescence
•3 sepals + 3 petals
•Superior ovary (carpel fusion varies)
•Drupe

•Unbranched trunks
•Big leaves on top!


Commelinid Monocots:

Zingiberales
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Large herbs with vessels more or less limited to the roots
Silica cells present in the bundle sheaths
Leaves clearly differentiated into a petiole and blade
Leaf blade with penni-parallel venation, often tearing between
the second-order veins
Leaf blade rolled into a tube in bud
Petiole with enlarged air canals
Flowers bilateral (or irregular)
Pollen lacking an exine
Ovary inferior
Seeds arillate and with perisperm (diploid nutritive tissue derived
from the nucellus)
8 families and nearly 2000 species


Characters of Poales
• Silica bodies (in silica cells) in the

epidermis
• Styles strongly branched
• Loss of raphide (needle-like) crystals in
most
• Much molecular support for monophyly
• Wind pollination has evolved several times
independently within the order
• Ecologically very important


Commelinid Monocots—Poales:

Bromeliaceae
(The Pineapple/Bromeliad Family)

• Tropical to temperate regions of the Americas
• Predominantly epiphytic herbs (“tank” plants)
• Diversity: ca. 2,400 species in 59 genera
• Flowers: radial, perianth differentiated into
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calyx and corolla, borne in axils of often
brightly colored bracts; inflorescences spicate
or paniculate; stigmas 3, usually twisted;
seeds often winged or with tufts of hair
Significant features: leaves with water
absorbing peltate (or stellate) scales
Special uses: pineapple (Ananas)

Family not required


Commelinid Monocots—Poales:

Cyperaceae
(The Sedge Family)

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Worldwide, usually in damp or semi-aquatic sites
Rhizomatous herbs, stems usually triangular in
cross section and solid
Diversity: 5,000 species in 104 genera
Flowers: with 1 subtending bract; tepals absent or
reduced to 3-6 scales or hairs; stamens 1-3; carpels
2-3 in superior ovary; fruit an achene (nutlet)
Significant features: Inflorescence a complex
group of spikelets; leaf sheaths closed, ligule
lacking; silica bodies conical
Special uses: Papyrus used originally for paper;
“water chestnuts” and a few other rhizomes edible,
leaves used for weaving; some ornamentals.
Required taxa: Carex, Cyperus